Schottky barrier diode and method for manufacturing the same

ABSTRACT

A Schottky barrier diode includes: an n+ type of silicon carbide substrate; an n− type of epitaxial layer formed on a first surface of the n+ type of silicon carbide substrate; a plurality of p+ regions formed inside the n− type of epitaxial layer; a Schottky electrode formed in an upper portion of the n− type of epitaxial layer of an electrode region; and an ohmic electrode formed on a second surface of the n+ type of silicon carbide substrate, wherein the plurality of p+ regions are formed to be spaced apart from each other at a predetermined interval within the n− type of epitaxial layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationNo. 14/952,186, filed Nov. 25, 2015, which claims priority to and thebenefit of Korean Patent Application No. 10-2015-0106106 filed in theKorean Intellectual Property Office on Jul. 27, 2015, wherein the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

(a) Technical Field

The present disclosure relates generally to a Schottky barrier diode anda method for manufacturing the same, and more particularly, to aSchottky barrier diode and a method for manufacturing the same capableof reducing on-resistance.

(b) Description of the Related Art

Generally, a semiconductor light-emitting device includes asemiconductor device capable of generating various colors of light dueto recombination of electrons and holes at a junction portion of n-typeof and p-type of semiconductors when it is applied with a current. Thesemiconductor light-emitting device has several merits over afilament-based light-emitting device, such as longer life, lower power,excellent initial driving characteristics, and higher vibrationresistance, and therefore, demand for the semiconductor light-emittingdevice has continuously increased.

Further, with the recent development of information communicationtechnologies around the world, communication technologies for super-highspeed, large-capacity signal transmission has become increasinglyimportant. In particular, wireless communication technologies, which isutilized in myriad devices, such as a personal mobile phone, satellitecommunication, military radar, broadcasting communication, a relay forcommunication, and the like, have been gradually expanded. Similarly,the demand for a high-speed, high-power electronic device required for asuper-high speed information and communication system of a microwaveband and a millimeter wave band has increased.

Further, research has been conducted to reduce an energetic loss whenthe semiconductor light-emitting device is implemented in a high-powerdevice. Except for silicon (Si)-based power devices, which is a commontype of power device, silicon carbide (SiC) devices having a large bandgap have also been widely produced as a Schottky barrier diode (SBD)structure.

The Schottky barrier diode uses a Schottky junction in which a metal anda semiconductor make a junction with each other without using the PNjunction, unlike a general PN diode, and has fast switchingcharacteristics and turn-on voltage characteristics lower than the PNdiode. The general Schottky barrier diode may cut off a leak current dueto the overlapping of PN diode depletion layers diffused at the time ofapplication of a reverse voltage and improve a breakdown voltage, byapplying a structure of a junction barrier Schottky (JBS), in which a P+region is formed, to a lower portion of a Schottky junction part toimprove the reduction characteristics in the leak current.

However, the conventional Schottky barrier diode suffers from a problemin that a contact area of a Schottky electrode with an n-epitaxial layeror an n-drift layer, which is a forward current path, is narrow due to apresence of the P+ region in the Schottky junction part to increase aresistance value and increase on-resistance of the Schottky barrierdiode.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the disclosure, andtherefore, it may contain information that does not form the related artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE DISCLOSURE

The present disclosure has been made in an effort to provide a Schottkybarrier diode and a method for manufacturing the same capable ofexpanding a contact area of a Schottky electrode with an n− type ofepitaxial layer, by forming a junction barrier Schottky (JBS) region byinjecting p+ ions into the n− type of epitaxial layer and then growinghigh-concentration n− type of epitaxial layer using epitaxial growth.

Embodiments of the present disclosure provide a Schottky barrier diode,including: an n+ type of silicon carbide substrate; an n− type ofepitaxial layer formed on a first surface of the n+ type of siliconcarbide substrate; a plurality of p+ regions formed inside the n− typeof epitaxial layer; a Schottky electrode formed in an upper portion ofthe n− type of epitaxial layer of an electrode region; and an ohmicelectrode formed on a second surface of the n+ type of silicon carbidesubstrate. The plurality of p+ regions are formed to be spaced apartfrom each other at a predetermined interval within the n− type ofepitaxial layer.

The plurality of p+ regions may each be formed with the same width.

Furthermore, according to embodiments of the present disclosure, amethod for manufacturing a Schottky barrier diode includes: forming ann− type of epitaxial layer on a first surface of an n+ type of siliconcarbide substrate; patterning a plurality of trenches to be spaced apartfrom each other at a predetermined interval in an upper surface of then− type of epitaxial layer; forming a first blocking part within theplurality of trenches; forming a plurality of second blocking parts tobe spaced apart from each other at a predetermined interval in an upperportion of the n− type of epitaxial layer; forming a p+ region byinjecting p+ ions into the n− type of epitaxial layer using the firstblocking part and the plurality of second blocking parts as a mask;removing the first blocking part and the plurality of second blockingparts; growing the n− type of epitaxial layer to enclose the p+ region;forming a Schottky electrode in an upper portion of the grown n− type ofepitaxial layer; and forming an ohmic electrode on a second surface ofthe n+ type of silicon carbide substrate.

Each of the plurality of trenches may be patterned so that a depth ofeach trench is shorter than a height of the n− type of epitaxial layer,

The plurality of second blocking parts may contact at least two firstblocking parts.

A side of one of the plurality of second blocking parts may be connectedto a side of the first blocking part.

The first blocking part and the plurality of second blocking parts maybe made of the same material.

The first blocking part and the plurality of second blocking parts maybe configured of an oxide layer.

The removing of the first blocking part and the plurality of secondblocking parts may be performed by a wet etch method or a dry etchmethod.

The growing of the n− type of epitaxial layer to enclose the p+ regionmay include: growing the n− type of epitaxial layer within the pluralityof trenches; and growing the n− type of epitaxial layer in an upperportion of the grown n− type of epitaxial layer and the p+ region.

Furthermore, according to embodiments of the present disclosure, aSchottky barrier diode includes: an n+ type of silicon carbidesubstrate; an n− type of epitaxial layer formed on a first surface ofthe n+ type of silicon carbide substrate; a plurality of p+ regionsformed inside the n− type of epitaxial layer; a Schottky electrodeformed in an upper portion of the n− type of epitaxial layer; and anohmic electrode formed on a second surface of the n+ type of siliconcarbide substrate. The n− type of epitaxial layer and the plurality ofp+ regions may be manufactured by any one of the methods formanufacturing a Schottky barrier diode as described above.

Accordingly, it is possible to expand the contact area of the Schottkyelectrode with the n− type of epitaxial layer, by forming the junctionbarrier Schottky (JBS) region by injecting the p+ ions into the n− typeof epitaxial layer and then growing the high-concentration n− type ofepitaxial layer using the epitaxial growth. Furthermore, it is possibleto reduce the on-resistance due to the increase in the Schottky contactarea and the presence of the high-concentration region at the time ofthe application of the forward voltage while maintaining the JBS effectas it is at the time of the application of the reverse voltage.

The effects which may be obtained or predicted by the embodiments of thepresent disclosure will be directly or implicitly disclosed in thedetailed description of the embodiments of the present disclosure. Thatis, various effects which are predicted by the embodiments of thepresent disclosure will be disclosed in the detailed description to bedescribed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a Schottky barrier diode accordingto embodiments of the present disclosure.

FIGS. 2 to 6 are diagrams sequentially illustrating a method formanufacturing a Schottky barrier diode according to embodiments of thepresent disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings. However, the followingillustrated drawings and the detailed description to be described belowrelate to certain embodiments among several embodiments for effectivelydescribing features of the present disclosure. Therefore, the presentdisclosure is not limited to only the following drawings and thedescription.

Further, in describing below embodiments of the present disclosure,well-known functions or constructions will not be described in detailsince they may unnecessarily obscure the understanding of the presentdisclosure. Further, the following terminologies are defined inconsideration of the functions in the present disclosure and may beconstrued in different ways by the intention of users, operators,practices, or the like. Therefore, the definitions thereof should beconstrued based on the contents throughout the specification.

Further, for efficiently describing the technical core features of thepresent disclosure, terms will be appropriately changed, integrated, orseparately used in the following embodiments to be clearly understood bythose skilled in the art, but the present disclosure is not limitedthereto.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Hereinafter, a Schottky barrier diode according to embodiments of thepresent disclosure will be described with reference to FIG. 1.

FIG. 1 is a cross-sectional view of a Schottky barrier diode accordingto embodiments of the present disclosure.

As shown in FIG. 1, a Schottky barrier diode 100 according toembodiments of the present disclosure is configured to include an n+type of silicon carbide substrate 30, an n− type of epitaxial layer 50,a plurality of p+ regions 70, a Schottky electrode 110, and an ohmicelectrode 115.

In the Schottky barrier diode 100, the n− type of epitaxial layer 50 isdisposed on one surface (i.e., a first surface) of the n+ type ofsilicon carbide substrate 30 and the Schottky electrode 110 is disposedin an upper portion of the n− type of epitaxial layer 50. Further, theohmic electrode 115 is disposed on the other surface (i.e., a secondsurface) of the n+ type of silicon carbide substrate 30.

The plurality of p+ regions 70 are formed inside the n− type ofepitaxial layer 50. The plurality of p+ regions 70 may be formed to bespaced apart from each other at a predetermined interval within the n−type of epitaxial layer 50, and each may be formed to have the samewidth.

In the Schottky barrier diode 100, the case in which the p+ region 70 isformed at the same width is described as an example, but embodiments ofthe present disclosure is not limited thereto. Therefore, the width ofthe p+ region 70 may be changed as needed.

Further, a longitudinal cross-section of the p+ region 70 may be formedin any one of a circle, an oval, and a polygon shape. For example, thelongitudinal cross-section of the p+ region 70 may be formed in aquadrangle shape as illustrated in FIG. 1.

Therefore, the Schottky barrier diode 100 according to embodiments ofthe present disclosure may greatly reduce on-resistance at the time of adevice operation due to presence of a high-concentration n+ region 30and an increase in a Schottky junction area while maintaining a junctionbarrier Schottky (JBS) effect by the p+ region 70. As a result, theSchottky barrier diode 100 according to embodiments of the presentdisclosure may improve a current density to reduce an area of the deviceand improve a device yield per unit wafer to save costs of the device.

A method for manufacturing a Schottky barrier diode 100 according toembodiments of the present disclosure configured as described above willbe described with reference to FIGS. 2 to 6.

FIGS. 2 to 6 are diagrams sequentially illustrating a method formanufacturing a Schottky barrier diode according to embodiments of thepresent disclosure.

As shown in FIG. 2, the n− type of epitaxial layer 50 is formed on onesurface (i.e., a first surface) of the n+ type of silicon carbidesubstrate 30.

In other words, to form the Schottky barrier diode 100, the n+ type ofsilicon carbide substrate 30 is prepared.

Next, the n− type of epitaxial layer 50 is formed on one surface of then+ type of silicon carbide substrate 30 by epitaxial growth.

Subsequently, a plurality of trenches 90 are patterned in a portion ofan upper surface of the n− type of epitaxial layer 50. The trenches 90are formed to be spaced apart from each other at a predeterminedinterval on the upper surface of the n− type of epitaxial layer 50, anda depth of the trench 90 may be formed to be shorter than a height ofthe n-type of epitaxial layer 50. That is, the trenches 90 are formed bypatterning while being spaced apart from each other at a predeterminedinterval at a portion of the upper surface of the n− type of epitaxiallayer 50.

As shown in FIG. 3, a first blocking part 91 is formed in the trench 90is formed. The first blocking part 91 serves to determine a form of thep+ region 70 when the p+ region 70 to be described below is formed.

Further, the first blocking part 91 prevents the p+ ions from beingdiffused at the time of the injection of the p+ ions to form the p+region 70, and may be differently formed depending on a size and a shapeof the p+ region 70.

Next, second blocking parts 93 are formed on the first blocking part 91and the n-type of epitaxial layer 50. The second blocking parts 93 areformed to be spaced apart from each other at a predetermined interval onthe upper surface of the n-type of epitaxial layer 50, and may be formedbetween at least two first blocking parts 91. That is, the secondblocking parts 93 may be formed between the first blocking parts 91 onthe upper surface of the n− type of epitaxial layer 50 and are formed tobe spaced apart from each other at a predetermined interval to form thep+ region 70 by injecting the p+ ions. For the purposes of the presentdisclosure, the second blocking parts 93 may include a single secondblocking part or a plurality of second blocking parts.

The second blocking part 93 configured as described above contacts atleast two first blocking parts 91 at the lower portion to form masksconnected to each other. The first blocking part 91 and the secondblocking part 93 may be made of the same material, in which the samematerial may be an oxide layer which is a hard oxide mask.

As shown in FIG. 4, the p+ region 70 is formed by injecting the p+ ionsinto the n− epitaxial layer 50 using the mask configured of the firstblocking part 91 and the second blocking part 93 as a blocking layer.

The p+ region 70 may be formed in a region of less than the depth of thefirst blocking part 91, and may also be formed to be deeper than thefirst blocking part 91. The p+ region 70 may inject the p+ ions onlyinto the desired position using the mask configured of the firstblocking part 91 and the second blocking part 93 as the blocking layer,such that the p+ region 70 may be formed at the desired size andposition.

As shown in FIG. 5, the first blocking part 91 and the second blockingpart 93 are removed.

A predetermined space is formed between the p+ region 70 and the n− typeof epitaxial layer 50 by removing the first blocking part 91 formed inthe n− type of epitaxial layer 50.

As shown in FIG. 6, the n− type of epitaxial layer 50 is grown toenclose the p+ region 70 by performing a crystalline re-growth processon the n− type of epitaxial layer 50.

That is, FIG. 6 illustrates re-growing the n− type of epitaxial layer 50so that a predetermined space formed between the p+ region 70 and the n−type of epitaxial layer 50 within the trench 90 is filled. At the sametime, the n− type of epitaxial layer 50 is grown so that it may also beformed on the p+ region 70. Therefore, the p+ regions 70 may be formedat a position where they are spaced apart from each other at apredetermined interval within the n− type of epitaxial layer 50. Next,the Schottky electrode 110 is formed in the upper portion of the n− typeof epitaxial layer 50 and the ohmic electrode 115 is formed on the othersurface (i.e., a second surface) of the n+ type of silicon carbidesubstrate 30.

As a result, the Schottky barrier diode 100 according to embodiments ofthe present disclosure manufactured by the above-mentioned method mayreduce the on-resistance due to the increase in the Schottky contactarea and the presence of the high-concentration region at the time ofapplication of the forward voltage while maintaining the JBS effect asit is at the time of application of the reverse voltage. Further, theSchottky barrier diode 100 according to embodiments of the presentdisclosure may further increase current characteristics by performingthe process as the desired line width without diffusing the p+ ions atthe time of the p+ ion injection process due to the first blocking part91 and the second blocking part 93.

While this disclosure has been described in connection with what ispresently considered to be practical embodiments, it is to be understoodthat the disclosure is not limited to the disclosed embodiments, but, onthe contrary, is intended to cover various modifications and equivalentarrangements included within the spirit and scope of the appendedclaims.

DESCRIPTION OF SYMBOLS

100 . . . Schottky barrier diode

30 . . . n+ type of silicon carbide substrate

50 . . . n− type of epitaxial layer

70 . . . p+ region

90 . . . Trench

91 . . . First blocking part

93 . . . Second blocking part

110 . . . Schottky electrode

115 . . . Ohmic electrode

What is claimed is:
 1. A method for manufacturing a Schottky barrierdiode, comprising: forming an n− type of epitaxial layer on a firstsurface of an n+ type of silicon carbide substrate; patterning aplurality of trenches to be spaced apart from each other at apredetermined interval in an upper surface of the n− type of epitaxiallayer; forming a first blocking part within the plurality of trenches;forming a plurality of second blocking parts to be spaced apart fromeach other at a predetermined interval in an upper portion of the n−type of epitaxial layer; forming a p+ region by injecting p+ ions intothe n− type of epitaxial layer using the first blocking part and theplurality of second blocking parts as a mask; removing the firstblocking part and the plurality of second blocking parts; growing the n−type of epitaxial layer to enclose the p+ region; forming a Schottkyelectrode in an upper portion of the grown n− type of epitaxial layer;and forming an ohmic electrode on a second surface of the n+ type ofsilicon carbide substrate.
 2. The method of claim 1, wherein each of theplurality of trenches is patterned so that a depth of each trench isshorter than a height of the n− type of epitaxial layer.
 3. The methodof claim 1, wherein the plurality of second blocking parts contacts atleast two first blocking parts.
 4. The method of claim 3, wherein a sideof one of the plurality of second blocking parts is connected to a sideof the first blocking part.
 5. The method of claim 1, wherein the firstblocking part and the plurality of second blocking parts are made of thesame material.
 6. The method of claim 5, wherein the first blocking partand the plurality of second blocking parts are configured of an oxidelayer.
 7. The method of claim 1, wherein the removing of the firstblocking part and the plurality of second blocking parts is performed bya wet etch method or a dry etch method.
 8. The method of claim 1,wherein the growing of the n− type of epitaxial layer to enclose the p+region comprises: growing the n− type of epitaxial layer within theplurality of trenches; and growing the n− type of epitaxial layer in anupper portion of the grown n− type of epitaxial layer and the p+ region.